It is known that periodic velocity variations superimposed upon the nominally constant velocity of a print head in a scan printing apparatus produce an image defect known as "banding". Inasmuch as lead screws are commonly used to move the print head during scan printing, the typical characteristic of lead screws to have subtle, once per revolution, errors manufactured into their threads, sometimes known as "thread drunkenness" unfortunately results in image banding.
Efforts at eliminating the effect of thread drunkenness on images produced by such scanning systems has resulted in requiring ever higher precision lead screws at higher and higher costs. Unfortunately, this has increased the cost of such printers while not entirely eliminating the problem.